1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) apparatus and, more particularly, to an LCD apparatus capable of optimizing the response speed of the liquid crystal molecules and a driving method for the LCD apparatus.
2. Description of the Related Art
Generally, an LCD apparatus includes a color filter substrate having a common electrode, an array substrate having a pixel electrode and liquid crystal disposed between the color filter substrate and the array substrate. When an electric field is applied between the common electrode and the pixel electrode, the arrangement of liquid crystal molecules interposed between the common electrode and the pixel electrode is changed. When the arrangement of the liquid crystal molecule is changed, the transmittance of light is changed in accordance with the arrangement of the liquid crystal molecule, so that an image may be displayed. s tend to exhibit moving pictures poorly because the response speed of the liquid crystal is slower than the period one of a motion picture frame, causing a moving image to become blurred. Therefore, it would be desirable to optimize the response speed of the liquid crystal to improve the display quality of moving pictures.
To optimize the response speed of a liquid crystal of the LCD device, a controller of the display device may operate in an overdrive mode in which over-compensated or under-compensated (higher or lower) drive current is provided to speed up the time to reach a desired brightness. To perform the overdrive mode, a dynamic capacitance compensation (referred to as DCC) may be used.
When the DCC is used, an overdriving value of a gradation datum may be determined based on comparison between the gradation datum corresponding to the preceding frame and a gradation datum corresponding to a current frame.
When using an overdrive circuit, a look-up table (LUT) that stores measured overdrive values is typically used since the overdrive value determined according to the comparison between current and previous gradation data does not change linearly with gray level owing to liquid crystal properties. In general, measurement of a compensation value (or overdrive value) stored in the LUT is carried out under the conditions that the vertical frequency is 60 Hz and the temperature is normal temperature.
A pre-tilting method may be used to optimize the response speed of the liquid crystal molecules. In the pre-tilting method, when images are quickly changed from a black gradation of a low voltage into a white gradation of a high voltage, the pre-tilt forming signal for pre-tilting the liquid crystal molecules is output, and then a high gradation signal that is higher than a target pixel voltage is output during a following frame interval.
In the pre-tilting method, an LUT is used, which has a plurality of pre-tilting values mapped therein corresponding to a current frame gradation datum and a following frame gradation datum. However, the LUT has a plurality of fixed pre-tilting values, so that the response speed of liquid crystal molecules between detail gradations is not optimized.